Definitely don't just roll over on their terms.
My DH is self-employed/contracts. If a client wants to change the terms of the initial agreement (work from home for X hours/days per month/week at a rate of X per hour/per day etc.) then the initial agreement is void and the negotiation over rates and terms etc. starts again.
Some small-medium businesses, especially if expanding rapidly, don't really have an idea about what's reasonable and how to handle freelances. They expect the perks of having an employee. So you need to tell them.
Agree, explain again to the CEO, slowly, that the hours & terms you initially agreed as mutually beneficial are not now on offer if he wants you in-office instead of home-based.
Don't worry too much about them looking elsewhere. If you've done good work so far it's probably more hassle for them to start again with someone new. You need to value yourself and your services highly as a freelance or no one else will, so be assertive (but nice
)
I would say something like:
^Dear CEO,^
^Following up on our last discussion about more hours and changes to the terms of your agreement with me, I'd just like to set out a few thoughts on your proposal.^
^On [XX DATE] you employed my services as a freelance to undertake [YY TERMS OF WORK AGREED] per [WEEK/MONTH} from home. We agreed a fee of [£ZZ] for the above.^
^If you would like me to now complete the work on location at your offices, I will need to charge a day-rate of [£ZZ] per day.^
^As also discussed, the estimate of hours needed for the work to be completed and the number of projects which I work on per [WEEK/MONTH] needs to be renegotiated, as the scope of the project has evolved - each piece requires on average [XX HOURS] research and [YY HOURS] writing.^
^I would be happy to discuss changing the way in which I charge you for work completed and efficiencies in workflow to give you the greatest value for money.^
^I'd just like to make sure that we're on the same page regarding the terms of my freelance agreement - obviously this relationship is slightly different to an employee of the company, and so I need to weigh up against my other clients the opportunity cost of devoting 3 full days in-office to your company. I would not be able to work for 3 days in-house on the current terms of out agreement.^
Yours...^^