Roofing question: which sealant to use to epdm (Sarnafil) roofing?

Can anyone give me a steer please? We have a 4 year old grey Sarnafil roof and one of the seals around the flashing is leaking into our kitchen where some creature seems to have chewed/pecked the sealant away (see photo). From what I can see online, epdm seems to need a specific sealant (and perhaps different brands need different sealants??) but I can't work out which. Any advice very welcome.

You can see the original sealant the roofers put in which cracked a bit and my builders added some other sealant over the top. I asked my original roofer but he got very defensive when I said there was a leak (all I wanted was some advice) and he won't return my calls or emails now .

Thanks so much. Phil