I have just held a ticket on the following route [all on one ticket]

KHI-DXB EK
DXB-x/NCL-x/LHR-YYZ EK/BA/AC
YYZ-LHR AC
LHR-x/DXB- KHI EK

It is a combination of an AC fare [change fee C$100] and an EK fare [1st change free, others PKR 1500.] The agent said if I purchase this ticket

1) no changes will be allowed. Although technically possible, she said that AC would point me to EK and vv in the even that I want to change anything and I wouldn't be able to change it at all.

2) If I miss my connection in NCL, I am SOL and might have to buy a new ticket.

Both of these statement are contrary to what I have heard on FT. I thought I would be protected if I misconnent in NCL since it is all on one ticket. Instead, she suggested to pay more and buy separate tickets.

Is she correct?
Any advice?

Cheers,