I bought one last week as a spare and to take on holiday. When we got it I put it together and put ds in to adjust the straps (14mo but in 6-9 clothes). The shoulder straps just didn't appear to lengthen enough, at their longest they met the buckle level with ds' chest.
Phoned o'baby who got me to measure the length (30cm) and they said it was faulty. John Lewis picked it up and gave a replacement. Same thing is happening. What am I doing wrong?!