They will just take your money and not activate your account.
You can't contact them securely, because their only support contact is email but the PGP key on their website is corrupted (you can't re-wrap the lines of a PGP key!) and even after fixing the corruption it turns out that they forgot to publish their encryption key (the published key is signing-only).
So there's no secure way to contact them.
Total waste of my time and money. This is why everybody uses Mullvad.
One secure way to contact them is through matrix. First, make sure the transaction was completed for the correct amount net of monero transaction fees.