can be a really pain, best thing you can do is create a new email and swap everything to that.
i have a similair problem with my mobile phone, i got 1 or 2 spam calls a month untill recently when i think i made the mistake of annoying a call centre worker who i think has put my number into some spam database i am now getting a dozen calls a day and nothing i can do about it
wish i could change my number but i still have 12 months of contract left when it looks like i will just sign up for new contract with new number rather than an upgrade
You can change your number for free. I had the same problem so phoned o2 and within a day or two had a new number. You can only change it once a year though, so don't be annoying any one else