Customers alleged that the download process, which requires a Wi-Fi signal, was taking a number of hours to complete.

Disappointed users posted their concerns on social networking site Twitter. One of them posted that the downloading process is so slow that ‘iOS 8 will be available by the time the iOS 7 update ends’.

Another user’s post reads: ‘43 minutes remaining to download iOS 7.0 but now 10 minutes later there is an error and I have to upload it again with another 2 hour wait’.