Excessive assessment pricing

Unhappy about the service, I dropped off a laptop on the 9th November and was quoted a fee of R450 for assessment, apparently if we needed it urgently the fee is R750, so I opted for the R450. I didn't get any communication about further costs when I called the store a few days later I was told that the laptop motherboard is gone and they unable to repair. I went to collect the laptop on Saturday and was quoted R750, nowhere on the receipt does it state R450 neither R750 these prices were verbally communicated with me. The customer service is pathetic and I'm seeking help further assistance due to the excessive amounts charged for assessment.