Unsolicited Marketing from odd phone number - "Stop" message will not send

I just got a marketing text from a hairdresser that I stopped going to a couple of years ago. I have tried to reply with "Stop" but the message sending is failed. The number that the text has comes is 10 digits long as you would expect from a mobile but starts with "276". Anyone know what kind of a number this is? I can of course ring them on their land line and ask them to stop texting, but I thought that it was a standard thing that you could just text stop or that they gave a clear method to opt out within the message?

Here's a link to the Data Protection Commissioner's website section about [broken link removed].

You are right, they are supposed to give you an opt-out. Not only that, they should have asked you in the first place if they could send you marketing information by text. And not only that, if you have not had a business relationship with them in the last 12 months best practice is that they should not still be maintaining your information.

Sadly it seems many many businesses are utterly clueless about this and are trawling their old records to find old mobile numbers to target in an attempt to re-generate business. In the last few months three different companies have targeted me in this way, it's really irritating.

that reminds me, i got a text recently from the place i got my wedding nails done in 2006, only used them the once, must try the stop thing next time i get it

I get similar messages from a similar profession and it seems to be sent from a landline. The business is in Cork and the number starts with 021. Does the number coming up correspond to local landline numbers?