Problem with flomasta shower drain membrane

Hello,

I wonder if I can get some advice here. I got Flomasta shower waste trap installed in my shower. It has got flat silicone membrane to stop the incoming odours, like the one attached. This membrane is keep failing every few years due to the fact that silicone deforms over time. I was keep replacing it with similar item made by wirquin which I was able to buy online, but now after I wanted to replace it again I found that this item is not available any longer anywhere.

I have done some further research including contacting my usual part supplier and they have told me that wirquin has replaced the silicone membrane solution by this part:

Filtering Outflow Membrane Replacement for Wirquin Slim Slim+ Drain Waste Traps

It is pretty expensive but I gave it a go, however I found that this part does not fit flomasta drains due to red plastic bit being too big. So I'm stuck now.

My question is if anyone has heard about any possible solution or if there's any way I can buy flomasta part? Replacing the whole drain is not on the table to to very difficult access to underneath the shower. I also don't want to buy whole Flomasta set just to get one part from it.

ANy ideas would be apprieciated.

Thank you