Home DIY

I'd get a quote for the remedial work. Then write to the bodge artiste saying:

1. The contract for the works contained an implied term that the work would be carried out to a reasonable standard.
   
2. The work done failed to meet that standard and require remedial works.
   
3. The remedial works will cost £x
   
4. Therefore you require a refund of £x in order to meet the costs of carrying out those works.
   
   

If you really want to go formal on his arse, state that the letter is a letter of claim pursuant to paragraph 6 of the CPR Practice Direction on Pre-Action Conduct and that you expect a response within 14 days.