Legacy tensioner replacment

[markp47]

Hi just need some help/advice

i have a 2010 subaru legacy love it and had a noise from the engine ,when i opened it the part in pic was vibrating alot

so i took it to my local subaru dealer and he said that it needs replacing which is fine BUT then he said that the bolts that hold it could snap and then it would cost 1000`s to fix the engine 

has anyone had a problem like this or heard of the breaking 

 

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