I have savings too. On a considerable amount I got maybe £150 over about 4 years. For the past three years my mortgage payments have been halved saving me about £15,000. I'd definitely take the low interest! It's the only reason we've been able to live since having Byron.
It sucks for your Dad. I'd argue the issue there is a shitty state pension. If as a nation we didn't expect pensioners to live on nothing their savings would be less important. It's disgraceful for retired people to be scraping together enough to live or, like my mum, having to work. My parents have little savings and little income.