Firstly, may I say you have my deepest sympathy’s. I have been investigating the issues in relation to our estate and have now instructed enforcement but this is after many months of investigations, searches and also reading the Planning Act. (not recommended as bedtime reading but great for insomnia)
My first advice is to write to the builders with your issues as you say you wish to do. Resister this letter and give them at a timeframe for reply, say four weeks. If you do not get a response, write again, requesting a reply to you original letter.
In the meantime, get a copy of the Planning Permission Schedule of Conditions and make sure what you have is the final permission. It would also be advisable to get a copy of the Planning Map to back up your case. Start to compile a report on the permission granted and the non compliant issues. If you still have no joy with the builders directly, issues this report to the enforcement section of the Council who granted the permission requesting official enforcement. Register this too. This is not an overnight process so be patient.
Mine is with still with the enforcement section who seemingly are obliged to act on instructions within six weeks, this remains to be seen. However, I am quite prepared to push this much further. I intent to p*** them off enough that they will complete the development to get me off their backs. During my investigation I came up with many other item which can cause them a lot more problems and I will use them if need be. It’s amazing what you find when you start digging.
I already have compiled a list of permissions being applied for by the builders in many councils of which I will be putting in objections to if our estate is not sorted.
Additionally, I know of one estate who were not getting any joy from the builders. They found out where the builders were launching a new development, so they decided to picket this launch. Their estate was soon finished off. This is not a route that I was prepared to take as I feel that the route I have taken will prove fruitful.
Best of Luck.