I don't even go into an MP with any more money than I intend to spend, let alone a bank card or credit card that could be run hard.
You have to assume (sadly) that MPs and SPs are run by a criminal element, and the value of your card information including PIN code is pretty high. You might as well write your info on 3X5 file cards and drop them in the local prison. That is the level of risk you are taking.
If you are intending to use a bank card, just go ahead of time and withdraw the cash.
if you are intending to use a credit card, might I suggest that you skip the massage and wait until you can really afford it?