[Company/ supplier address]
[Reference: address where work is taking place]
I am writing to complain about the service you provided when I asked you to prepare [describe plans] for, and supervise the work at, the above address.
When I first spoke to you on [date], I made it clear that I wanted the work to proceed as follows: [describe]. It has now become apparent that the service you have provided is deficient in the following respects: [describe].
Also, the Consumer Rights Act 2015 requires you to carry out your service as an architect with reasonable skill and care. The problems described above show that you failed in your legal obligations. I therefore have a claim against you for breach of contract.
Because of your breach of contract I have suffered [describe losses and inconveniences caused]. I am now looking to recover the total sum of [£....] in respect of the above losses from you.
I therefore look forward to hearing from you in the next 14 days.