The Consumer Rights Act 2015 gives you protection and can be used to resolve this issue, either with he company concerned or, if they do not give you satisfactory replacements / repair, through the small claims court (maximum claim £5,000).
The fact you have not yet paid for the doors (and any installation work?) Shackeng rather complicates any possible claim you have as the doors are still technically and legally owned by the installation company. Therefore, because of this impasse you have, with the installer not agreeing to replace / repair the doors after your repeated requests, which you should have done in writing, giving them reasonable notice (30 days) to resolve the issue or you will be taking legal action ( with a separate letter from you giving "Notice of Action"), I would consult with professional independent advisors, such as the Glass and Glazing Federation (GGF) and the Double Glazing and Conservatory Quality Assurance Ombudsman Scheme (DGCOS). Dependant on the trade bodies this company belongs to, I would also contact them for advice.
I would also read the advice given by
Which? :
www.which.co.uk/reviews/double-glazing/article/how-to-buy-double-glazing/your-rights-when-buying-double-glazing
If you had paid for the doors and installation the claim would be straightforward, but in law the doors do still belong to the supplying company (but, also dependant on what type of contract you signed with this suppler and any relevant clauses on the transfer of ownership of the doors vs. payment) it rather complicates your claim. However, one fact is for sure you ARE entitled to have supplied and fitted a good and satisfactory pair of doors that conform to any claim made before the contract was signed, and whatever is considered reasonable in law.
All the best with your action
Read more:
https://www.which.co.uk/reviews/double-glazing/article/how-to-buy-double-glazing/your-rights-when-buying-double-glazing - Which?