Replacement mushroom vent

The mushroom vent cover for the shower fan in a Broadway FB 2016 has fallen off, has anyone got any ideas where we can get a replacement?  We have tried Autosleeper parts without success.
Thanks if you can help.

Have you tried the forum introduction section? 
They are very good at sourcing parts.

Thank you.

For a start have you tried Spinney ?

I have no idea what the vent looks like that AS fitted but this one is available from lots of suppliers on eBay..
https://www.ebay.co.uk/itm/Mushroom-Roof-Vent-Caravan-Motorhome-Boat-Comet-12v-Electric-Fan-Ventilator-/324381944042?mkcid=16&mkevt=1&_trksid=p2349624.m2548.l6249&mkrid=710-127635-2958-0

Paulmold wrote:I have no idea what the vent looks like that AS fitted but this one is available from lots of suppliers on eBay..
https://www.ebay.co.uk/itm/Mushroom-Roof-Vent-Caravan-Motorhome-Boat-Comet-12v-Electric-Fan-Ventilator-/324381944042?mkcid=16&mkevt=1&_trksid=p2349624.m2548.l6249&mkrid=710-127635-2958-0

That looks just like the one on my Gloucester.

Thanks for the response re the vent cover, I am awaiting to hear from Spinney and I have tried the Autosleeper website for parts and they have advised I will need a completely new motorised vent at £50.52 - the vent cover does not come separate!  Plus the one on ebay has 3 screw holes in which is not really suitable as I don't want to start drilling holes in the roof.  I've put a heavy duty piece of plastic over the hole and used a jubilee clip to keep in place until Autosleeper has the parts in stock. 

Just in case anyone else suffers from a detachable cover for their shower vent fan, this cover fits perfectly. But I did add some silicon sealer to stop it coming off again!

https://www.leisureshopdirect.com/ventilation/camper-van-conversion/vents-miscellaneous/roof-ventilator-12v-spare-dome-and-connector