Don't know what to do anymore

Very frustrated with this dealership. I've only had good service from them in the past, but the last time my Suzuki Baleno was serviced my service booklet was never put back into my car.

I had a full franchise service history on the vehicle and all my services were done at this dealership. I've phoned repeatedly over the last months to find out if they can find it or what the next steps are if they can't. Every time I phone the person answering the phone just says they'll phone me back, but I never get a call back. Eventually after numerous calls they told me that they can't find the service booklet so they will need to issue a new booklet, restamp it and I will have to cover the cost of the booklet out of my own pocket, which I just agreed to out of desperation with the hopes that this issue will finally be resolved even if I need to pay for someone else's mistake.

I waited a few months and started phoning again to enquire on the progress of the booklet, but again the same issues. I'm honestly so disheartened at this point and just don't know what to do anymore. I just want this resolved as I have a full franchise service history and it will depreciate the value of the vehicle if I can't prove it with the service booklet.