Before anything else, make sure that the problem is genuinely caused by the ISP. In particular, use the SPIP discussion lists to ask if other users have experienced similar or other problems with the given ISP.
Secondly, if the problem has been confirmed to originate with the ISP, contact the supervisor or the support desk and ask if it’s possible to modify the configuration so that it’s compatible with SPIP. This can often be the case with modules and associated packages employed by SPIP. Already many ISPs have revised and tweaked their configurations to better suit SPIP users, and you may well succeed if you make your case clearly.
Lastly, as a last resort, when you’re sure that your ISP can not or will not modify their configurations to make it more compatible with SPIP, you’re now here asking if there are SPIP-side patches that can be used to render the system compatible with restrictions imposed by an ISP. Well, sorry, but No, there aren’t. The over-riding priority of the development team is to avoid a proliferation of such "patches", "fixes", and "work-arounds" by playing with the system code. The aim being to deliver a unique version that everyone can use (ease of installation is one of our highest priorities). If your ISP isolates particular faults with SPIP, we’ll investigate to see if we can resolve the problem and then incorporate the solution into the next general release.
As a final note, there are many free and non-free ISPs that easily and gracefully accommodate all of SPIP’s features, and migration of a SPIP site is finely detailed elsewhere in the documentation.