I do sympathise with your plumber. There are so many different brands on the market these days, that unless the customer knows from whom the tap was purchased or what the brand is, it may be very difficult to locate parts. So many unmarked brands are coming from Asia and Europe by the crate load and dumped on the market that spare parts really do become and issue. So I would suggest that if you purchase any tapware, buy from a credible source, keep all receipts and documents especially if the tap does not have the manufacturers stamp on it.