Think the last three posters have got a good point, it’s really not expensive and should really be considered as part of the fuel costs rather than maintenance.
There is also the extra costs the scheme incurs by getting the dealer to top it up, dealers being dealers are going to charge far more than the local car spares place or supermarket, throw in admin costs etc and come end of year accounts it must work out rather expensive for Motability.
Of course if there is a genuine reason that it has to be done by the dealer then fair enough but for everyone else just because you can get it done for free doesn’t mean you shouldn’t do it yourselves.