It is virtually impossible that your PulsaCoil appliance can create high bills, providing it has been correctly installed. Unless you physically press your ‘boost’ button to charge the unit during daytime hours, your unit will only heat on the off peak period and you should be able to identify this cost clearly on your electricity bill.
Most people will notice a significant difference in their electricity usage during the summer months when they do not make use of electric radiators. High electricity bills are far more likely to be linked to your domestic appliances or heating system.