Call transfer on DAHDI channells

All channels on Asterisk configured as DAHDI channels.After customer make payment I want to transfer the customer to the representative who interact customer before.

I try to make it by Dial() command. This is the dialplan

exten => s,1,Set(TRFNUM=${CALLERID(num)}) exten => s,2,Set(TRFNAME=${CALLERID(name)}) exten => s,1,AGI(agi:// exten => s,4,Dial(DAHDI/1/${TRFNUM}&DAHDI/2/${TRFNUM}&DAHDI/3/${TRFNUM}&DAHDI/4/${TRFNUM}&DAHDI/5/${TRFNUM}&DAHDI/6/${TRFNUM}&DAHDI/7/${TRFNUM}&DAHDI/8/${TRFNUM},30) exten => s,5,Hangup

For example: Call comes to DAHDI/1 after the payment DAHDI/1 dial all channels one them Answer the others Hangup. DAHDI/1 bridge call by with DAHDI/2. However, although Customer and representative close phones, Channels do not Hangup. They stay Busy.

Where do i make mistake. I should hangup call channels or find another way to transfer.