Car comes back with issues after service - Bosch Service

Thought I would take my car in for a service through Bosch. They gave me a quotation and I booked in my vehicle. My vehicle had no issues before it was booked in it just needed a good service. So a major service was done with the full 21 inspection check and everything. They only came back to me regarding a v-belt that needed replacement which I was happy with. Upon collection of the vehicle, they said all was well and there were no issues or problem. Drove the vehicle and had no issues as we don't stay too far away. Don't use the vehicle that often due to the lockdown and mainly drive our other vehicle. Took the car out the other day just for a drive and all of the sudden when accelerating there is very little power and it stutters. Call Bosch back and told them there is an issue with the vehicle. They gladly said no worries I can bring it back in and they will have a look. Went in today, the mechanic drove the car and noticed the issue. He told me it is the HT leads and the ignition coil that is not firing correctly and needs to be replaced which really made me upset and disappointed as it didn't have any issues before the service. Now all of a sudden I need to replace this and the cost to do this is more than the major service and still have the audacity to charge for a car was. Really disappointing and especially in these times all they can say is sorry for the inconvenience.