It is possible to cancel the contactless on your debit card. Call them and kick a fuss, they will send you replacement card which will not work for contactless. Banks are not keen in making this info public, for obvious reasons.
As for me, I don't use the joint acocunt for most of my punting, but it is still possible to request cash back at supermarket checkouts, etc so you could still get money out this way, witohut anything obvious showing on your bank statement (Cash backs are usually included within your supermarket spend and do not even shown as an ATM Withdrawal). The only thing that could give you away is the actual supermarket receipt, which shows the cah back as a separate line, and some of the stores will get you to initial that lin, to prove that you have received the cash back and signed for it.
