Measuring Cups

Measuring Cups can be a diabetic's best friend.  We recently purchased a set of measuring cups since we only had one.  We've only used them a couple times and the ink from them is always washing off!!  What's the point of a measuring cup if it can no longer measure?!  Of course, who saves receipts for measuring cups but that's just not fair.  I think I will be sending an email soon for a refund.