Corrupt data causing slow wifi

My wifi has been slow on my iphone 5s even though it is showing as full strength. After following the instruction online and talking to apple support multiple times, they concluded that I have corrupt data on my iphone. After restoring my phone multiple times, as they requested, they told me that i cannot recover my data as previously told. At this point, I can't restore my phone and am left to start this off as a new phone. Has anyone else had this problem? Does anyone know some sort of solution?