At the beginning of July I had the battery changed on my Fiat 500 (with Halfords Autocentre). Since then my bluetooth, phone connection(s) and start/stop have all stopped working and my mileage won't stop flashing.

On Google's recommendation I disconnected the battery, left for 10/20 mins, and reconnected. Nothing! So, I took it back to the autocentre that changed the battery - they were stumped as to what the issue was and advised that perhaps it was a different issue that coincidentally occurred at the same time I had the battery changed. Not so sure, I took the car to a different Halfords Autocentre for a second opinion - they tried allsorts but the problems still remained. They advised I contacted Fiat. On contacting Fiat, I was told it wasn't coincidental that this has happened but it is in fact very odd. However, understandably, they need to look at the car to be able to figure out the issue. It's going to cost me £72 for the privilege though! That is before any work is done.

I am wondering where I stand with this legally. I gave Halfords a perfectly serviceable car when I sent it in for a battery change, and they have given me back one that isn't. Who is liable? I am reluctant to spend more money on it when I really feel Halfords should be rectifying the issue, and if they are unable to (due to expertise) then they should be compensating me for this?

Any thoughts or guidance is much appreciated!