Appliance Repairman

Please consider this letter before you even call to this company.
My experience;
We made an appointment with this company, the person on the phone said that we have to pay $ 80 for a FULL diagnosis, or they can discount it if we sign a contract, we agreed on this and they gave us a time frame; the next day from 10 AM to 1 PM to find out what is the problem with our Bosch 500 series dryer. The next day we waited around 12:30 and called them again to find out why no one had appeared, receptionist told us that they made a time correction; from 2 PM to 5 PM (nobody warned us about any changes).
The repair man (he is just over twenty) appeared at about 2 pm, his diagnosis was; turn the dryer ON and after a couple of minutes turned back off, after which he noted that the heating element of the dryer is faulty and it needs to be replaced. In fact, I've known this before, even I've called them, but the difference now is, I have to pay $80 for it a few minutes of "diagnosis" or accept their terms and pay full price.
Discount 80, Labor costs 280, parts 486.24, and the total cost CAN 775.45 including tax.
They refused to make any adjustments to the price after we discovered that the spare part for this device costs only 112.87 US dollars, and we decided to terminate the contract, they stated that they will charge us labor cost (280) in accordance with the policy, even they did not do any labor.