When you say you're seeing 10% decline rates, is that out of your total transactional volume (which I suspect is the case), or just out of the subset of your customer who actually have bona fide Visa credit cards?
I'm British, and we have both Visa Debit and Visa Credit in the UK. I haven't yet looked into whether it's Visa Debit or Visa Credit or both which is experiencing issues.
Occasionally a spike up to 10% failure rate of all our card transactions (sorry, misunderstood your Q). ~80% of our transactions are VISA of some sort.