Not sure if this is the correct place to post. Basically i am in dispute with the company who factor our estate. Due to a late payment I was charged a factors fee on my next bill. I actually got the final demand letter for the previous bill the day after I paid the invoice. I had also told them payment would be late. I called the factor to discuss the fee and it was agreed that if I paid by X date the fee would be waived. I have this all in an email. Gratefully I paid straight away. To my surprise this week I received a final demand to pay the late payment fee. Assuming it was a mistake I called then be told that due to me not setting up a ddm they decided to charge me. The email does recommend a ddm but in no way says this must be done. Is this legal. Surely if they offered to waive the fee in writing and I met the terms offered they can't now decide to not keep to the agreement. I am currently in talks and have been told it has been referred to the director. It's not a lot of money it just the principal. I have had a fee wavied in the past due to another bill dispute and this is what they now keep referring to. This was all discussed at the time of coming to this agreement. Should I just pay or insist they keep to their side of the bargain.