OK, I held back a while before posting here again and following up on this saga.
The initial charge of $1.99, which I agreed to, was deducted from my visa card, so that was OK. I was holding back from posting on here further until I could see what had happened and I am pleased and relieved to say that the unasked for subscription was cancelled without any further charges against my card, so all has turned out fine.
As you said, lots of $1.99s do add up in the long run, but I can handle that - I would have been taking further action had the full subscription been charged, though.
I did ring the bank, just to be sure that all was OK and they said they couldn't do anything until and / or unless a charge had been made to my card. So everything has turned out fine in the long run.