How to complain about a builder who took the money and vanished

You paid a builder up front, the work is a mess or unfinished, and now they won't answer the phone. This drafts a formal letter before action: what they did, what the Consumer Rights Act says about it, what you want, and the deadline, so it reads like the last step before court because it is.

Write a formal letter before action to [trader name / company] regarding work carried out at [my address] between [start date] and [end date]. The agreed price was [amount]; I paid [amount paid] upfront. The work is defective because [describe faults]. Under the Consumer Rights Act 2015, services must be carried out with reasonable care and skill. Demand that they return to remedy the defects by [deadline], or refund [amount] so I can engage another contractor. State this is a letter before action and that I will pursue the matter through the county court small claims track if unresolved.