Premium Bonds holders have been cautioned that turbulent times may lie ahead for the popular savings product. This comes after recent changes were announced by provider NS&I to its monthly prize draw structure. NS&I has informed savers that it will boost the prize fund rate from July's draw, rising from the current 3.3 per cent to 3.8 per cent. The odds of winning for each £1 Bond will also improve, shifting from 23,000 to one to 22,000 to one. [...]