Uniconnect Sim — Network signals suck

Network signals suck --- I was visiting London and my friend gave me his already bought uniconnect sim card for london saying its pre paid and still functional, i'll just have to recharge it.. Super excited that my sim worries were taken care of but when i landed and changed the sim, there were minimal signals and calling was difficult. Ultimately I had to call the customer support centre for help and they said everything is fine on their end and it shd get better which onviously it didnt. Am glad atleast i didnt buy that sim.. Pathetic experience