If’s worth trying another dealer, my local one always amazed me with how cheap they would do some bits of work.
I enquired about replacing a headlight bulb last winter and they said they’d do it for the cost of the part, no labour charge. Even better the cost of the part was less than anything I could find online.
I needed a new coil pack once it was about a year outside its warranty. They knocked off a massive percentage of the cost of the part. It started off with 50% knocked off, then when it came to the final bill the guy knocked another chunk off to round it down. The labour charge was something comically low like £2.93.
Since you mention a tick my Corsa’s engine does make a ticking noise, it has done since I’ve owned it at 6months old. The dealer (a different one to which I bought it from) managed to convince me this was normal after taking me out in a new one which made exactly the same noise. Does anyone else’s do this? Its a 1.2 Corsa D