Engine Light nightmare

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Codes indicated O2 Sensors needed to be replaced 2X's in 24hrs. 1st.hint of a rat. Codes still indicated more emission issues. Car was running fine but was told ECM was fried and had to sent out of state for replacement 2nd hint of a rat!. Was told that would take 3 days and 3 weeks later ECM was still not right. 3rd hint of a rat. (It takes a matter of minutes to reflash a new, used or refurbished ECM. You can get an ECM on Ebay even) But it still took another week and a half. Got it back Thursday the 14th and yesterday engine light came back on. Mechanic had to replace the MAF this morning. Shouldn't there have been a scan before letting the car go and taking final payment. No engine light now but I think they saw my brother n law as a sitting duck. Does this unusally unfortunate domino effect smell like a rat to you?