Using Mail on 10.3.9

Am attempting to open a Bankwest account.

The Area Code box , after entering 08 (required in a single specific box) reverts to 8. Have tried all permutations but

My app then rejects.
The same thing happened I recall when trying a similar procedure with CommBank some time ago

Any answer out there please.

Tony Wilson
27 Ambridge St
Hamersley  WA  6022
Tel 08 9448 1517