I work for large web hosting company as senior system administrator, we usually ban malicious websites because we receive complains from 3rd party. I do such web site bans every day and I'm aware what web hosting companies will look for in your files also how and where attackers/hackers are hiding their backdoors.
Usually I got paid a lot more for similar work but as this is my first bid as freelancer I'll do it for far less and mostly because of the fame, I'll do my best to clean your files once for all, the rest really depends on your account security like control panel/ftp passwords.
About the ETA, it's depends how many files your web site have and how deep the malicious code is spread, this could take from 30 minutes to 48 hours as I'll review each of your web site scripts.
If you choose me, then please keep in mind that I will only clean the malicious code from your web application files.
Have nice day !
Regards,
Kostadinov