Work changed my resignation date

[Amap]

I'm leaving due to being treated poorly, I have been offered a better position somewhere else, it's a 4 week notice period but due to the start date at the new company I asked my work if they would accept 3 weeks notice, they agreed and confirmed my last day in writing, so then I confirmed my start date at the new company and signed the contract. I have now had someone higher up in management tell me that they need the full 4 weeks and they have told me I have to stay for the extra week. I can't. I've confirmed my start date in my new job and signed the contract. I'm leaving my old job and going straight into the new one.

Work are now telling me that I have to stay the extra week and that it's in my contract to give 4 weeks notice and if I don't they will take action against me.. but they agreed in writing my last day now they are telling me I have to stay a week longer. I've been a good employee for them for years and since I've handed in my notice I am being blamed for leaving them short staffed. I'm stressed.. can they take action against me if I leave on my planned date?

Dear Employer,

Due to the start date for my new position I asked whether it would be possible to leave after three weeks' notice instead of four. My request was granted. Please see attached the written confirmation from Sue Brown that my last day is 31st December.

I will be leaving on that date as per our written agreement and I expect to be paid in full for each day actually worked, as well as my outstanding annual leave balance. If I am forced to take legal action against the company because it has failed to honour its basic legal obligations towards me, I will also be exploring whether I may have a case for constructive dismissal, given that the reason for my resignation is the fact that I have been persistently mistreated at work.

Kind regards,

@Amap

They won't take action, it's not worth it and they are bullshitting you.

In my last job I wouldn't do the three months, gave them a month and then walked. They threatened me with legal action. They did nothing.

Yup this.

I will also be exploring whether I may have a case for constructive dismissal, given that the reason for my resignation is the fact that I have been persistently mistreated at work

please leave this part out. It will devalue the rest of your communication as it's untrue and inaccurate.

the time to have accused them of CD is not when they know you're already leaving for a new role. You can't just add CD in randomly, for good measure and expect them to take you seriously!

Email the earlier confirmation of end date to your personal email so you have a copy of it. Email it to your manager and HR and reiterate that this us the pre-agreed date that you're leaving. Then leave on that date.
They can't do anything about it and they won't do anything legally as they don't have a leg to stand on (one of my managers once left the company with zero notice - just walked out!)

If it’s confirmed in writing then there is nothing they can do.

Write back to them stating that they have confirmed your proposed termination date and, on that basis, you have confirmed a start date with your new employer and to change that now could negatively affect your future employment. Then state that their threat of action against you is extremely high handed and you will have no hesitation in taking the matter to an employment tribunal if necessary.

What I suspect they’re hoping to do is deduct pay from you punitively but in my opinion a tribunal would take a very dim view of this. Hold firm but make everything formal in writing, keep copies and evidence of posting etc, and if you do have to file with a tribunal, ensure you do so within their strict time limits (3 months last time I checked).

Tell them to fuck off. They aren’t going to take action against you for the sake of a week. They are just trying to put the frighteners up you and it’s working.

Speak to citizens advice or use the legal coverage on your homeowners or renters policy.

OP. If you have your last day in writing and backed up, they can't do anything.