Should Avast! be detecting & removing these?
Malware Bytes detects them but they return. Spybot do not appear to detect them.
avast will detect them as PUP if you have PUP checking enabled.
Malware Bytes detects them but they return.do you mark them for removal?.....and they still return?
if you need help removing it, see instructions https://forum.avast.com/index.php?topic=53253.0
attach Malwarebytes / Farbar Recovery Scan Tool / aswMBR logs
when done a removal expert will assist you… there may be some waiting time so be patient 
Thanks Eddy - tried as you suggested - enabled PUP - Avast! did not detect - scanned folders to double check - still no detection. Richard.
Hello Pondus - starting your advice process.
A PUP is only detected when executing it, not true a scan.
wrong , PUP detection is default enabled in boot scan … and those who have not turned on PUP detection usually see it for the first time when doing a boot scan
W32:Evo-Gen [susp] = Suspicious / this is a on access detection only, you will not see this in any scan or at VirusTotal
that said, there was one case where it did back in 2012, guessing it was a signature bug
https://www.virustotal.com/nb/file/ddd5c1664227acae6952f831c51c3f4e3a8fcbf2a54a2917fd7a86c38acdf1a6/analysis/
Thanks for your advice & support. Issues resolved thus:
Revo Uninstaller enabled me to remove Smart Bar which Windows 7 uninstaller couldn’t.
The Farbar tool showed that an XTRM Group item was running (via task manager) which once forced to close enabled me to delete it.
All issues appear resolved.
Ran CC Cleaner to clear up any loose ends.
I recommend attaching farbar logs and let a malware expert review them