Currently at war with the Victoria & Alfred Hotel in Capetown, which will not stop emailing me

For the last six years (since October 2017) I have been receiving unwanted sporadic emails from various email addresses related to Newmark Hotels in South Africa. I don't seem to be able to stop it for any length of time.

It looks like someone used my email address to create an account. This means that unsubscribing doesn't actually work because if that person makes a booking the hotel will continue to send the booking information by email, even if they stop emailing marketing stuff. So I have recently been getting booking information for someone else, who was staying at the V&A hotel. Apart from being annoying it also seems like a privacy problem or security flaw.

"Please note if you unsubscribe from the Newmark Hotels email list, we will continue to send you important, time-sensitive messages related to recent transactions, such as reservation confirmations." 

😬

Presumably the person also managed to get their booking information, somehow, as I later got an email inviting me to give feedback on 'my' recent stay.  Or perhaps it was automated and the person didn't get their info and didn't manage to stay at the hotel.

All attempts to contact the hotel or the chain through various email addresses to try and nip this in the bud (too late) hasn't worked and there seems to be no way of stopping them from emailing me. I've had to set up filters on my email so their future attempts will bypass my inbox.

I'm sure the venue itself is perfectly adequate for hotel stays but persistently emailing people who aren't interested doesn't warm me to them.

Tried leaving a message on their Instagram account too but it was rejected as spam, so the war continues ;)