Warning with product in Australia - They will not offer any replacement and instead insist that their highly stretchy $15 extender strap for running is suitable. My experience in the pool is that the HRM Swim rolls down your body each time you turn in the pool trying to use this "fix".
The customer support team can't offer any other form of support so don't waste an hour of your time waiting for an answer.
Signs of diminishing customer service run by badly designed scripts and planning.
Does anyone have any alternative ideas?