Fiona Mainwaring, probate department manager at Shropshire law firm Martin-Kaye Solicitors, said a series of recent high-profile court cases had highlighted the dangers.
Solicitors have increased their share in the will writing market over the past four years, despite growing concerns of an increase in poorly drafted wills by unregulated will writers.
Fiona, based at Martin-Kaye’s headquarters in Euston Way, Telford, said: “There has been a spate of cases recently involving wills drafted by unregulated providers which have caused serious problems.
“For example, Barclays has this year been sued by Tinuola Aregbesola, who claims that a botched will deprived her of a stake in her late father's London home. It was drawn up using the bank’s £90 will writing service, which is unregulated.”
Latest figures show the use of will writing services provided by banks and other organisations has declined from 8.7 per cent in 2009 to 5.9 per cent in 2015, and is continuing to fall.
Fiona added: “It is evident from national research that the public prefer to use a solicitor to write their will, wherever possible.
“They are aware that, with a solicitor such as Martin-Kaye where we have a dedicated probate department, you can be assured of a valid will and if anything does go wrong, there is proper insurance and redress.
“This may not be the case with an unregulated provider and certainly isn't the case if you take the DIY option, and decide to write your own will. It may save you money in the short term, but with the average estate in the UK now standing at £160,000, it could be hugely costly if you only find out too late that the paperwork is flawed.”
“An off-the-shelf will may seem very attractive, but it can be a risky approach - if errors are made, or if the strict witnessing rules are not followed correctly, the document could be invalid.
“And the implications can be serious. Not only might you risk leaving your family with a financial and emotional mess, but your legacy could be eaten away by legal bills or unnecessary tax.”