Mac adware advice please!

[rendelharris]

Could anybody kindly help me with an adware problem I have on my iMac (27", 2013, running ElCapitan, all updates installed)?

Some days ago I thoughtlessly clicked on what looked like an Adobe update, only to realise too late that it wasn't...as a result I got some irritation called "helperbar" on the computer. What it does is harmless but deeply irritating: it puts links into text to try to make one click on them, and when one opens new pages (in Firefox) it frequently opens an extra page of adverts alongside.

I've downloaded Malwarebytes Anti-Malware and it identified and wiped the thing, everything worked fine for a while then it started again. Ran Malwarebytes again, it identified several new names and wiped them. Again, worked fine for a while, then started again. Now at the stage where I have to run Malwarebytes every half hour or so, the same thing always popping up under different names.

Does anyone have a solution to this please? If so I'd really, really appreciate knowing it!

Many thanks,

Rendel