If you don't mind me asking, what was the amount ?

Hello all, I've seen a similar topic covered in previous posts but they were long ago and I'm wondering if the advice is still relevant. I've been receiving conflicting information so I wanted to check here. I have approximately £7000 in credit card bills from Barclays. I was living in the UK at the time under a work visa. I left the UK to move back home to Canada approximately 2 years ago. My financial situation has changed and I will be informing them that I cannot pay as of right now. I will be updating them on my out of country address (although I believe I already have). What means do they have to collect? Should I be concerned?