Welcome to JA.
I am sorry to hear about your situation.
Please note that this is not a chat service therefore you may experience delays but rest assured that I will respond within 24 hours.
The Consumers Rights Act states that services provided must be performed with reasonable care and skill. Where services are provided are not done with reasonable care and skill then the consumer can exercise a number of remedies.
One of the remedies is specific performance which means that the service provider returns to fix the issue at no costs to you.
In view of this and the fact you have a second opinion which states the service provided by wickes was below standards it appears your rights have been breached.
Therefore you should obtain a written report from the person that stated that wickes provided a cowboy to do the works. Send the written report to wickes and also remind them of your rights under the Consumers Rights Act.
Assuming they do not accept your position I suggest you consider filing a complaint with the trading standards and homes improvement ombudsman.
Alternatively you can consider court action against wickes. With regards ***** ***** action I suggest you consider instructing a local commercial solicitor to assist you with this process.
I hope I have clarified the position.
Thanks and stay safe.