Where to buy new part for Siemens Washing Machine?

I’ve broken the cap that screws in under the service flap on the front of my washing machine (at the bottom on the right hand side as you look at it). It’s a white, plastic cap, about 6 or 7 cms in diameter (it might be called the pump cover).

I’ve googled and looked on this site, but with no joy. Can anyone tell me where’s a good place to get Siemens’ spares from? And also what it’s actually called.

For info the washing machine is a WM14S382GB, just under 4 years old.

Thanks,

Michael