Spamming their client, no unsubscribe.

I have been spammed by multiple sales agents wanting me to upgrade a product that I don't even use anymore. Sage decided to make a quick buck off the Vat increase to sow fear into their clientele so that they upgrade to a newer product. What they neglected to do was put an unsubscribe on all of their emails. I have sent messages back asking them to remove my contact details yet i still keep on getting automated replies from their sales agents. I am on the verge of going to the direct marketing association to lodge a complaint