I had a conservatory built last year but the roof has always leaked. Although the builder has been back a couple of times he hasn’t been able to fix it, he’s now avoiding me.
If you think the leak can be fixed quite simply and cheaply you will probably be better off getting in someone who knows what they’re doing to make the repair and forget the builder. If the problem is more serious a design fault perhaps or faulty materials you may have to have a report prepared by a surveyor and threaten to sue the builder unless he puts things right. If he fails to respond within a given time, say 14 days, you can ask another firm to repair the conservatory and attempt to recover the cost from the builder, bear in mind that this may be easier said than done.