I need my script to edit and force write read-only files

I have a script that alters lines in files. Which was working fine, but from hence forth, files will be read-only. I've tried changing wq to wq! (as I would in VI) but this has seemingly no effect. I've also tried "zz" which also did nothing.

I appreciate any help; thank you.

debug=false

## *****Put file name in quotes******
declare -a arr=("UF19905217" "UG19905218" )

##Put date in DDMMYYYY format for the date the message was original processed.
DATE="25082015"

## now loop through the above array
for i in "${arr[@]}"
do
    #if "$debug; then
        echo "Fix file named: Inbound_$i.msg"
        MSG="Inbound_$i.msg"
    #fi

    if [ ! -d "$MSG" ]; then
    # Enter what you would like changed here.  You can copy and paste this command for multiple changes

        #DATATYPE
        printf "%s\n" ',s/<DataType>EDI<\/DataType>/<DataType>830<\/DataType>/g' wq | ed -s  /data1/Inbound/$DATE/$MSG        

        echo "Complete"
    else
            echo "Message not found or errored!"
    fi

done