No monthly package being received by myself but their debit order goes through every month.

I applied for a cellphone contract( a two year contract) last year around August and i only received my phone in December. What happens is usually on the 5th of every month I'd get my monthly package, airtime and data. But ever since April my contract sim card stopped working and I've been trying to get hold of them but nothing. Their landline rings till it takes me to voicemail and for them it's business as usual as their debit order goes through every month.