Servicingstop

Booked my service and mot a month in advance then called day before to say they had no garage available. Then that they could do it on the 8th July which is the day my mot ran out. So i agreed as long as they were definitely picking it up and doing it on that day. I am disabled and NEED my car to get out of the house which they knew about.
I got a phone call from them to say i needed a front coil spring replacing which it did so that was fine but also it apparently needed special grade engine oil, break fluid, spark plugs and a few other things at a total of £630... i told them i could not afford this and ill do the other less urgent repairs when i can. He told me this is important to keep the car running properly and not causing anymore damage but to pass my car it was still going to cost me £369 which i paid as soon as i got the message to pay it and i was told my car would be delivered back to me the same day. It comes to 5pm and still no car or phone call to say they couldn't bring it back that day. Finally got my car back at 11am the next morning and spoke to the guy from local garage who told me its not service stop who pick the car up and do the work, they don't even see the car or know what needs doing to it unless its a failed mot. He told me the garage he works at charges £160 for a service and mot whereas service stop charged me £90 so service stop upsell their customers to recoup money they lose from that. I said that wasn't very honest at all and its disgusting that they would lie to their customers like that especially when they've been told that you cant afford it. He told me that service stop look at the mileage a car has done and guess when you need parts so they tell you that you need them in the hope that you will have the work done and they can recoup money from it. I find this disgusting and deceptive and I WILL NOT BE USING SERVICE STOP AGAIN.