2 percent 10th prox-net 30 days?

We use this, which in our invoicing means our TERMS are

in the invoice is paid within ten (10) days you can deduct 2% from the total

but we expect the total within thirty (30) day. Some customers used the confusion

excuse to take the 2% when they paid in thirty days. We also, then said interested of

(X) would be added after 60 days.