Towbar electrics fuse ratings

Hi, just hooked up my van to the new car with the supplied 13 pin to 7 oin adapter and blew a fuse. On checking I found it was 15 amp that was blown, so I replaced it and fitted the adapter again, this time without the van attached, same problem. The book that came with the car says that fuses 43, 44, 45 should be 15, 20, 15.

Was wondering if anyone else had this fault and any solution. I'm thinking that the fitter has got the fuses mixed up as all the wiring at the plug is correct.

Any help would be great.

Thanks

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