Hi there! My name is Adam. I assume that someone hacked your hosting account (if I do understand 'bad scripts' properly).
I'll clean your hosting account from malware, I'll also secure it - I'm able to secure any version of Joomla. It is what I can do for sure.
If you want me to upgrade Joomla everything depends on current version, installed template and installed add-ons (like plugins, modules and components).
Send me please your site URL and I'll be able to send you more details.
I am highly qualified for this project - I have a 3+ years experience cleaning and securing hacked websites/hosting accounts. Actually, I do it on daily basis as a freelancer. I'm a server admin in my full-time job, where I also manage few Joomla installations (upgrades, modifications, solving issues etc).
If you have any question, just drop me a message or let's discuss details on chat.
Best regards,
Adam