The ticket cannot be legally enforced MM...ignore it completely.
Do not enter into correspondence with them.
This company will send you a couple of follow ups that seem authoritative but they have absolutely no chance of enforcing it.
I have put a link below...read those forums and then throw the ticket in the bin.
Most hospitals, retail parking spaces, etc are on private ground and the parking is run by private companies who cannot enforce a ticket.
If issued with a council or police parking ticket I would pay but I certainly wouldn't pay any of these companies.
http://forums.pepipoo.com/index.php?s=ca2977c85e7f2c2d269a113591d2a074&showforum=60ETA the company you mention MM are another of these private companies. I suggest you join the forum I linked to and post about the above-they will give you great answers backed by fact.
I used them when I sold a car and the new owner was subsequently found driving it without insurance and the police, in their wisdom, charged me. They gave me great advice that was bang on and saw the case being dropped and an apology given to me.