For starters, you'll need to put a DISABLE INTERRUPT before your readMB ISR.
Otherwise the Interrupts will keep interrupting the ISR.

And, the CREN bit (RCSTA.4) needs to be toggled (cleared then set) to clear a OERR or FERR condition.
Your routine simply turns the receiver off (RCSTA.4 = 0), and no further data will be received.