Fitting inner tubes to Rover 200?

I have a Rover 200, 216sli, N reg. I have to inflate the tyres every 3 or 4 days due to the original alloy wheels being pitted etc.

I cannot afford new wheels and to me the obvious solution would be to fit inner tubes, but my local "Quickfit" state that this is not possible.

Is it possible to do this or can anyone suggest a solution to this problem.

Many thanks

John