Sony Xperia C3 Virus Monkey Test and Time Service

Hi,
I've a Sony Xperia C3 having some virus of random download of application, which after searching found two applications Monkey Test and time service are culprit for same.

Solutions Referred-
-Factory Reset done with "Automatic Restore" uncheck (Application are there even after restoring):rolleyes:.
-After restoring disabled the service and no uninstall option was there (Now play store is not opening):mad:.
Questions:
-What is firmware re installation?Is it re installing andriod OS?
- Will this remove the virus i've mentioned?
- what tool or application will do this (Searched one PC Companion, is this the one).
- Can anyone provide step by step reference or any video to do this

Thanks & Regards
Harsimran