Add popping up at same time

Relative newcomer to Kodi and in main very impressed (16.1).
Have encountered a major issue that is very annoying/frustrating.
Ads keep popping up during both playback and on opening screen in what appears to be regular intervals of 6/24/45/124 minutes. The back button clears the advert sending me back to the “choose stream” menu where I can resume playback and reset audio.
Only a recent development but oh so frustrating.
Anyone know what to do to remove the ads please?
Thanking you in advance and kindest regards
Mike