Bad costumer service

On 03 August 2023 I placed an order on shein nd on the 29 August 2023 I received an email stating that my parcel have been lost nd I have to contact Buffalo international Logistics which I did but their phone keeps on ringing nd I did tried to communicate with them on whatsupp and the massges did went through but no one is replying .....I'm really stressed and I don't know what to do.