I refuse to pay a for a bill for technical support if the service was horrible and I ended up doing most of the work. How do I go about this issue?

I refuse to pay a for a bill for technical support if the service was horrible and I ended up doing most of the work. How do I go about this issue?
It is advisable to write a formal letter of complaint to the company concerned. In the letter state clearly and factually what the issues were with the service, what you had expected and what in your opinion did you not receive for the payment demanded.
Request that they look in to the matter over the next 14 days and reply to you with what they believe they have done to be able to bill you for the service and what refinements to the the cost they are prepared t make as you would expect to pay (i your words nothing) as you did all then work sorting the issue. Remember to keep copies of the communication, send the communication in manner which makes them sign for it on receipt and keep a note of all emails, calls etc made between you.
Names, dates and times are essential to build a realistic argument - Never threaten