Drainage Issue -Blocking toilets in houses

We live on the new build estate which now unfortunately has a daily visit from a drainage truck to take away our waste as the pipe is not sufficient enough for the house on this development - Southern Water are now not responding but Taylor Wimpey are trying to get hold of them to fix the issue. If you can help it would be great, we now have toilets that cannot flush, shower drains that do not empty etc also the smell from the truck is out of this world.

Thank-you Zack