Argos requires authorisation from Hotpoint to issue a replacement product or to send for repair. It sounds like an inherant problem which as the product was made by Hotpoint rather than Argos then Hotpoint should be the one to pay for any repairs. This is why Argos will pass you on to Hotpoint - it might be an idea to ask a CSM at Argos to phone up Hotpoint on your behalf and explain that you feel this is an inherant problem and as it is a fault in their manufaturing.
Argos cannot accept responsibility for poor/defective manufacture from external companies.
Hope this helps.