Hello Ian,
I missed this thread and certainly didn't realise that it was from a 'local'.
Sorry to hear of your costs I have had my Bongo for nearly two years now and I haven't needed to spend that much - having said that its booked in for its second MOT a week friday

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I had intended to do as much servicing as I could but all I have managed to do is oil change and electric bits and a few modifications. (too many other demands on my DIY skills!). I have posted a reply to a local thread in the Scottish section regards servicing - but in short I'm taking it in to Westhill Service Station on thursday for coolant change, gearbox fluid change and brake fluid change and I was quoted £92 + parts (I have my own coolant) + VAT - i.e. about 3 hrs work. I though that wasn't bad.
They have worked on Bongos before and I spoke to the fellow who had a head gasket blow that they repaired and he was quite happy with the result and no problems since.
Regards the alarms mentioned earlier in this thread - I have fitted the MAson alarm / temperature gauge modification which only takes about 20 mins plus a bit of driving around to get the setting right. I have also fitted a coolant level alarm but not the type mentioned. If you want to see / hear these in opperation I'll be happy to take you for a run aound if I can think of a hill steep enough to trigger it
As you have already spent a rather lot of cash on your Bongo I agree with the others about keeping it but I would strongly recommend fitting the alarms to avoid the dreaded overheating - I wouldn't like to see that be the 'final straw'.
If there's anything else I can do please PM me - I can't be far away from you.
Regards Grahame