VFS, which has its headquarters in the UAE but is owned through holding companies in Jersey, the Cayman Islands and Luxembourg, faces claims of “gross maladministration” and “aggressive” selling of optional services since taking the UK government contract in 2014.

During that time, the Home Office has made £1.6bn from applicants looking to visit, study or be reunited with their families – a nine-fold increase on the five years prior to the start of the contract.

A joint investigation by The Independent and Finance Uncovered found the amount the department makes on average per visa application has increased from £28.73 to £122.56.

VFS, which is contracted to process visas from all countries outside Europe and Africa, handles applications to work, study and live in the UK, as well as visit.

People applying through VFS – the majority of whom are from lower-income countries, with a quarter from south Asia – have said they missed flights and were wrongly denied visas due to delays and administrative errors, including apparent failure to scan vital documents.

Others said they had faced a barrage of “optional” services on the VFS website, ranging from document checking for around £5, to a “super priority” visa service costing as much as £1,000, which some said failed to deliver on the fast-tracked service promised. Lawyers said these additional services could exploit vulnerable migrants who may feel pressured to spend more to secure visas.