If you are paying �14,000 a year for maintenance - it sounds like the Freeholder should be responsible for at least some maintenance. However, exactly what he is responsible for will be set out in the terms of your Lease - this may not include plumbing etc.
It does sound like your Freeholder is trying to pull a fast one by seeking posession after such a short time. Have you not received any request or notice to carry out remedial works?
You need to get a copy of your Lease, and, as meglet says, get some legal advice from a solicitor. Best of luck.