The replace my battery with an old dead battery

i took my phone to melrose arch wefix branch , for them to replace my battery , after replacing the the battery i was told the charging port is faulty and it will cost R650 to replace the new one but i can still use it the mean time . the following day my phone stop charging .

so yesterday i took my phone to another shop to replace a charging port , when i get there we discover that the battery wefix put in is dead and its very old . i then confronted them .

they told me that because it was open by the third party they cannot help me. i find it very strange , because it simple means i was not suppose to see that they put an old battery which also imply that they did this on purpose .