you don't need to contact your isp provider, all you need to do is log in your modem router via website, go to your settings, check if you have a dynamic ip or static ip under internet settings, in most cases everyone has a dynamic ip, sometimes users get a static ip but its rare, plus you would need to pay a monthly fee for a static ip. You can easily change your ip via modem router yourself, you dont need to ask your isp provider to do it.
Also like i said just don't log into your banned accout on your new pc. You need to create a new steam profile.