Weak GSM signal indoor

After I took my phone in for repair charging block my Huawei P8lite Have Bad signal then it shows Emergency calls only or No Service But at Certain Spots it Finds A little bit Signal in bathroom Only H+ And in town it gets 4g Its signal is very bad... Before I took it in for repair I didn't struggle with the signal it was 100% working... After I took it in for repair the charging block I struggle with the Signal. I did take it back to them they check what's wrong they said they accidently broke my Anthenna /signal Anthenna they show me it is a Small silver thing... They repair it For free they said because they broke it... But Nothing changed.. Still struggling no service or Emergency Calls only... Please I need Help