By the way Boxbilling doesn't work. It returns PHP errors. I might actually invest in WHMCS at some point as I know for a fact that'll work. Thanks for all the help guys.

I tried The Hosting Tool. It's good for a free software. However it will not suit my needs I'm afraid. So yeah, WHMCS is probably the best bet as that's a great piece of kit. But it's also one of the most expensive ones.

Nevertheless, if you think about it, it's worth it.

You should consider Account Lab Plus. It is the most advanced open source billing software that you can find. In addition you can install Account Lab Plus through Fantastico. There is one more alternative phpcoin. So I think you should try these options as well.

I think, actually, when I decide to get round to installing an automated billing software, I will invest in WHMCS.

It really is the best program. I think it would be the sensible option if I want to make sure things work properly.

It may be a good software but a free tool can never compete a paid one and specially WHMCS. So, for best result you should be carrying on with it.