[Company/ supplier address]
[Reference: contract number or service reference number]
I refer to our previous [correspondence/conversation] in which you have stated your contract allows you to [give details of what the contract enables the company to do].
Specifically you seek to rely on the following term in the contract: [give details of the term in question].
I consider that this term is unfair pursuant to the [Consumer Rights Act 2015 OR Unfair Terms in Consumer Contracts Regulations 1999] for the following reasons: [set out your basis for challenging the terms]
For the reasons stated above, this term is not enforceable against me.
[Set out the consequence of the term not being enforceable, for example are you entitled to some money back or are you saying that the trader is not entitled to additional sums that they're claiming?]
I look forward to hearing from you in the next 14 days.