Hi there

I'm no car expert so apologies if I'm not very clear, just looking for some advice.

I bought a Citroen C5 2.0 HDI (2004) diesel second-hand two years ago and have run it with no problems since - it's a lovely car.

But a few months ago we noticed that the coolant temperature sensor was occasionally swinging up or down wildly, then returning to normal.

Last week while getting brake pads replaced at a local garage (that I've used before) I asked if they could replace the sensor too. They did it, saying they'd used a generic part (rather than Citroen official part) and to let them know if any problems.

Then on Saturday we were driving locally and noticed masses of steam coming from under the left-hand side of the bonnet and a burning smell.

When breakdown arrived they said that the coolant was empty and there was lots of liquid sloshing around the bottom of the car. They couldn't do any more diagnosis on the road but thought it was a coolant leak.

I took it to the original garage today - they fixed it saying that the end of a water pipe had blown off (I should have asked exactly which part but didn't) they'd replaced the pipe head and refilled the coolant (and charged £75).

When I drove the car home, as I pulled in to the drive, I noticed steam coming from under the bonnet again, and the same burning smell...

What do you think I should do next?

I've got limited ability to test the car myself, and I don't know whether I can trust the local garage now - they've always been fine before, but it seems a bit of a coincidence there's a leak just after they replace the sensor :(

Can I ask the original garage to look at it again for free, should I go back to them expecting them to charge me again, or should I try going somewhere else?

Thanks for any advice! :(