To my surprise my package price is gone up by £12 after 6 months. Reason given is that a discount on certain product has expired after 6 months. I was not aware of any such expiration when I signed up for a new contract on a fixed price given for 1 minimum 12 months.
So I want to continue at he original price or cancel my subscription for all the services.
Your rights depend on what was offered in the call when you agreed to this. If VM offered you a discount for a new twelve month contract, UNLESS STATED OTHERWISE you'd reasonably expect that to last for the same time. Suggest you raise a complaint (search Virgin Media complaints code of practice), requesting they reinstate the agreed discount, AND twenty quid for the hassle because they withdrew it. Do the complaint in writing and include a statement that you cannot discuss this on the phone, and all communication must be in writing. If they refuse (or just keep delaying and messing about) you can escalate to the industry arbitration service CISAS (and then ask for £50 compensation, reinstatement of the discount and refund of any "overpayments" they've already taken by direct debit.
The published data from CISAS suggests VM have an appalling record of holding out until CISAS are involved, and then caving in. But because VM have eight weeks to resolve a complaint before you're allowed to escalate, they'll be hoping that most people give up.
Sadly this isn't a quick fix, but when you need to fight a bureaucracy like VM, you have to follow the processes.