hello
I have a coin operated system on my air con in an apartment used for holiday rentals,
it was expensive to buy and install but has worked perfectly for 3 or 4 years, it has never jammed and has never been broken into either, if you think being broken into is a problem you should really have a think about the type of people you imagine renters to be
I considered the card option but decided against it for a number of reasons, like card supply and repaying credit hassle but know that they work fine as well
I know how to get a coin meter and have it fitted for you and could find a card one for you as well,
the difference in price is about €100