stop calling me lancet and demanding money poor service

i took my child to the hospital knowing that my medical aid will cover all the expenses as they checked at the hospital before the child was admitted. Then it happened that the was shortfall regarding lancet. i have told them several times that i wont be paying as i should have been informed because i know that i do not have the money to pay. now they are busy calling me everyday non stop please stop harassing me and know that i wont be paying as i should have been informed that the would be shortfall and now i do not have the money to pay.