It is always a hassle when the 50Rp pieces fall through 5 or more times until you can pay your parking fee - or you don't have the right coin. Most of the time it's about fees under 2 CHF.

-- I would welcome it if, for example, you could load the Cumulus card with e.g. max. 20 CHF and pay the parking fee that way ...
-- or even better, when paying at the cash desk /Subito station, the parking fee for the desired time could free up the exit ticket.

I usually know how long I'm going to be in the shopping center .... and if I happen to meet a friend on the way to the car after paying, then I'll have to pay extra at the information desk... ;-) This payment method would really be a customer service, especially for me, who has no reasonable choice of coins in my wallet apart from the 5Räppler (which are also not accepted) .... ;-)