I left the policy map statements out as I don't see the relevance to a pure bandwidth swap.

You can find this script also in the infoblox-toolkit github: github/setbandwidth.ccs

Feel free to fork and improve!

########################################################################
## Export of Script: Change bandwidth on interface
## Script-Level: 3
## Script-Category: Uncategorized
## Script-Language: CCS
########################################################################
Script:
	Change bandwidth on interface

Script-Description:
	'Script to replace bandwidth from one value to another on interfaces and sub-interfaces that start with an octet.
    Old bandwidth, new bandwidth and octet(s) have to be provided at runtime'

Script-Filter:
    $Vendor eq "Cisco" and $sysDescr like /IOS/

Script-Variables:
	 $networktochange   ipaddress   "Replace bandwidth for interfaces and sub-interfaces that start with this octet"
	 $oldbandwidth      int         "Bandwidth value to look for (integer in kb)"
	 $newbandwidth      int         "Bandwidth value to replace the old one with (integer in kb)"

########################################################################
#   Check if interface is in network we want to change                 #
########################################################################

Action:
    ShowInterfaces

Action-Description:
    List interfaces and filter for the octet we want to limit the script to

Action-Commands:
    SET: $updatemade = "no"
    show ip int br | include $networktochange

Output-Triggers:
    Get Interfaces

########################################################################
#   Check if interface has BW value we want to replace                 #
########################################################################

Trigger:
    Get Interfaces

Trigger-Description:
    Trigger to parse out the interfaces from show ip int brief, extracts most types of interfaces and sub-interfaces.

Trigger-Variables:
    $IntName /\w+\d+(\/\d{1,2}|\/\d{1,2}\/\d+|\/\d{1,2}\.\d+|\/\d{1,2}\:\d+)?/

Trigger-Template:
    [[$IntName]]\s

Trigger-Commands:
    show interface $IntName | include ^_.MTU_.+_BW_$oldbandwidth

Output-Triggers:
    Parse Bandwidth

########################################################################
#   Check if interface has old BW value and update to new one          #
########################################################################

Trigger:
    Parse Bandwidth

Trigger-Description:
    Trigger to parse out the bandwidth from show interface, extracts bandwidth for evaluation

Trigger-Variables:
    $CurrentBandwidth int

Trigger-Template:
    BW\s[[$CurrentBandwidth]]\s

Trigger-Commands: {$updatemade eq "no"}
    SET: $updatemade = "yes"
    conf t
    interface $IntName
    bandwidth $newbandwidth
    EXPR: $counter = 1
    exit

Trigger-Commands: {$updatemade eq "yes"}
    interface $IntName
    bandwidth $newbandwidth
    EXPR: $counter = $counter + 1
    exit

########################################################################
#   Write the new config to memory                                     #
########################################################################

Action:
    Save Config if a change was made

Action-Commands: {$updatemade eq "no"}
    LOG-INFO: No Change was made

Action-Commands: {$updatemade eq "yes" and $counter eq 1}
    LOG-INFO: One interfaces has been updated
    PRINT: $counter interface has been updated
    end
    write memory

Action-Commands: {$updatemade eq "yes" and $counter > 1}
    LOG-INFO: Multiple interfaces have been updated
    PRINT: $counter interface have been updated
    end
    write memory