Sorry to hear of your problems. Some landlords can be a pain.
These problems by themselves *CAN* be solved. Sit down and talk to your landlord. If he doesn't attend to you and/or the problems, write to him. Also get a lawyer to send him a letter.
The Tenancy Agreement allows for rectification works after you have done the necessary - notifying the landlord, allowing for time to let him organise labour for repair works, etc. After you have served enough notice on the landlord, you may proceed to get repairs done. May I suggest you do it properly : get a few quotes, and each time keeping the landlord informed by Registered Mail. Take photos. Keep all invoices.
You will not be allowed to offset expenses paid for repairs from the monthly rental. The lawyers will be able to advise.
Finally, the construction next door of a 27-Storey block is not enough reason to break the lease.
B.Mgr