Leave your current web host when their services turn bad. Definitely, there is nothing much you can do at your side. Some hosting is growing fast, and others is dieing fast. Find the right hosting.Some web hosting company is good, and later turn out to be bad, poor service, and try to rip off the new customer. Beware and make sure you know when its time to leave the current hosting.
Second sign, when the customer support is not reachable frequently and always late in replying email ticket. This is the second sign. When on averagely the service quality drop, there will be lots more other users complaining to the technical support. And they will be so busy to answer each of the email. Usually they will just delete it off. If your email ticket got deleted, you are mostly at this stage.
In my opinion third and final sign, search online for similar user problem. And usually at the hosting forum, you will find similar complaints. If that’s what you are seeing, and there is no action taken to fixed your current problem. Time to pack your website and move out. There is no point to royal to these hosting.